Piano with loud speaker on secondary sound board



PIANO. WITH LOUD SPEAKER 0N SECONDARY SOUND BOARD Original Filed June 19, 1929 IN VEN TOR. I W. M

A TTORNEYS.

utilizing a piano Patented dark. 10, 1933 PATENT OFFICE JOHN HAYS HAMMOND, J'B., 0F GLOUCESTER, MASSACHUSETTS IBIANO WITH LOUD SPEAKER ON SECONDARY SOUND BOARD Application filed June 19, 1929, Serial No. 372,078. Renewed October 6, 1932.

This invention relates-to pianos, and more particularly to a piano havin a loud speak ing device associated therewit The invention provides mechanism for as a support for a loud speaking device which may be actuated by a radio receiving set or other convenient means.

The invention further provides for the use of a loud speaking device without interfering otherwise impeding the normal operation thereof.

In accordance with the resent invention a secondary sounding boar is mounted on the piano in such a position that it is acoustically separated from the usual piano sounding board. The secondary soundin board may be separated from the sounding oard oi the piano by a sound insulating arrier which prevents vibrations of the strings from being transmitted to the loud speaking compartlllbllt and likewise prevents the vibrations produced by the loud speaker from acting on the strings. Means is also provided "for mounting the loud speaker on the secondary sounding board in an efdcient manner and for causing the vibrations thereof to be transmitted to the various parts of the sounding board. The invention also consists in certain new and original "features of construction and combination ct parts hereinafter set forth claimed. y Although the novel features which are believed to be characteristic oil this invention will be particularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages, the mode of its operation and the manner or" its organization may be better understood by referring to the following description taken in connection with ilzhe accompanying drawing forming a part thereof, in which Fig. 1 is a plan view of a piano partly in section showing the location or the loud speaking device and the strengthening ribs secured to the secondary sounding board; and

Fig. 2 is a side elevation partly in section of a piano showing the secondary sounding to hoard and the sound insulating barrier.

with the acoustic qualities of the piano or .ing compartment from the normal operating causes the same to vibrate, thereby amplifytion of the compressional waves which are Like reference characters denote like parts in the several figures of the drawin In the following description an in the claims parts will be identified by specific means for convenience, but they are intended 5 to be as generic in their application to similar parts as the art will permit.

Referring to the drawing more in detail the invention is shown as applied to a grand piano 10 having a keyboard .11, sounding board 12, strings 13 and frame 14. The particular construction of the above mentioned elements of the piano form no part of the present invention and are accordingly not set forth in detail. I

Below sounding-board 12 there is mounted a bafie 15 of sound insulating material which serves as a support for the speaker to be described, and separates the loud speakcompartment of the piano. A secondary sounding board 16 is mounted below'bafie 15 and is provided with means for securing a loud speakin device 17 thereto. Said device. 17 may be oi any convenient form suitable for producing compressional waves of audio frequency in response to a varying electric current. The frame or chassis of the loud speaker 17 is preferably rigidly secured to soundin board 16 and the normal weight of the spea er is carried by springs 19 which extend from said chassis to baide 15.

The sounding board 16 is preferably formed with an opening (not shown) adjacent loud speaker 17 whereby compressional waves produced by the armature thereof maybe propagated to the surrounding medium. The reaction of the chassis is also transmitted to the sounding board 16 and ing the compressional waves produced by the armature oi the speaker. For this purpose the loud speaker may be secured to the sounding board either -r mechanically or phonetically. An acoustic coupling can be secured by proper relative disposition of the sounding board and loud speaker even though they are not mechanically interconnected. This is thought to be due to the actransmitted between the diaphragm and the sounding board. The term phonetically is understood to apply to this acoustic coupling. The vibratlons produced by the spea er are thus transmitted either as direct mechanical vibrations to the sounding board or as compressional waves from the speaker to the soundin board. In either case the sounding boar is caused to vibrate and to am lify the waves emitted by the speaker.

or transmitting the vibrations more readily to thevarious parts of the sounding board and causing the same to vibrate as a unit, there are. provided a plurality of ribs which radiate from speaker 17 to the various parts ofi said sounding board. These ribs areso arranged that the vibrations of ,the various frequencies are transmitted equally over the sounding board whereb the normal tendency of the sounding boar to be selective of a definite range of frequencies is reduced to a minimum.

Convenient means for operating the loud speaker is shown as a radio receiving set 21 having its input circuit connected to an antenna 22 and its output circuit 23 connected to said loud speaker 17. It is obvious, however, that the loud speaker may be actuated from other sources if desired.

Bafile 15 separates sounding board 12 from sounding board 16 and prevents interaction between vibrations of the two sounding boards. This rmits either a loud speaker or a piano to K used in a normal manner without distortion. By mounting the loud speaker on a separate sounding board secured,

to the piano, advantage is taken of the normal acoustic qualities of the piano and at the same time the necessity for a separate article of furniture containing the loud speaker is avoided.

While certain novel features of the invention have been shown and described and are pointed out in the annexed claims, it will be understood that various omissions, substitutions and changes in the forms and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is: v

1. In combination with a piano having strings and a sounding board, a second sounding board a loud speaker phonetically associated w1th said second sounding board, and means whereby the vibrations produced by said 5 eaker are transmitted to said second sounding board and amplified thereby.

2. In combination with a piano having strings and a sounding board, a second sounding board, a loud speaker phonetically associated with said second sounding board, means whereby the vibrations produced by said s eaker are transmitted to said second sounding board and amplified thereby, and

1,aes,eea

means for preventing interaction between said soundin boards.

3. In com ination with a piano havin I strin and a sounding board, a secon soun ing board, a loud speaker phoneticall associated with said second sounding boar means whereby the vibrations produced by said s eaker are transmitted to said second sounding board and amplified thereby, and a baflle inte osed between said sounding boards and orming a sound insulating barrier whereby interaction between said sounding boards is prevented.

4. In a piano having a plurality of strings and a sounding board, a sound insulatin baflle mounted adjacent said sounding boar a second sounding board mounted adjacent said baflie and forming therewith a second sound chamber, a loud speakin device mounted in said sound chamber an adapted to pro agate compressional waves, and means where y said waves are transmitted to said second sounding board and amplified thereby.

5. In a piano having a plurality of strings and a sounding board, a sound insulatin bafile mounted adjacent said sounding boar a second sounding board mounted adjacent said bafile and forming therewith a second sound chamber, a loud speaker secured to said second sounding board, means for supportin the dead weight of said speaker from said baflle, means for propagating compressional waves from said loud speaker and causing said waves to be amplified by. said second sounding board.

6. In combination wtih a piano having strings and a sounding board, a second sounding board, a loud speaker phonetically associated with said second soundin board, means whereby the vibrations pro need by said s eaker are transmitted to said second sounding board and amplified thereby, said second sounding board having radial ribs extending from saidloud speaker whereby vibrations of said speaker are more readily transmitted throughout said sounding board.

7. In combination with a piano, a loud speaking chamber carried by said piano and sound insulated therefrom, a loud speaker mounted in said chamber, and means whereby compressional waves produced by said speaker are propagated to the surrounding medium.

8. In a piano having an operating compartment containing strings and a sounding board, a loud speaker compartment containing a second sounding board, and means for sound insulating S3.l( compartments whereby independent operation thereof may be ob tained.

In testimony whereof I have hereunto set my hand.

JOHN HAYS HAMMOND, JR. 

